1. Field of the Invention
The described embodiments and invention as claimed relate to oil and natural gas production. More specifically, the invention as claimed relates to a downhole tool used to selectively activate in response to fluid pressure.
2. Description of the Related Art
In completion of oil and gas wells, tubing is often inserted into the well to function as a flow path for treating fluids into the well and for production of hydrocarbons from the well. Such tubing may help preserve casing integrity, optimize production, or serve other purposes. Such tubing may be described or labeled as casing, production tubing, liners, tubulars, or other terms. The term “tubing” as used in this disclosure and the claims is not limited to any particular type, shape, size or installation of tubular goods.
To fulfill these purposes, the tubing must maintain structural integrity against the pressures and pressure cycles it will encounter during its functional life. To test this integrity, operators will install the tubing with a closed “toe”—the end of the tubing furthest from the wellhead—and then subject the tubing to a series of pressure tests. These tests are designed to demonstrate whether the tubing will hold the pressures which it will experience during use.
One detriment to these pressure tests is the necessity for a closed toe. After pressure testing, the toe must be opened to allow for free flow of fluids through the tubing so that further operations may take place. While formation characteristics, cement, or other factors may still restrict fluid flow, the presence of such factors do not alleviate the desirability or necessity for opening the toe of the tubing. Commonly, the toe is opened by positioning a perforating device in the toe and either explosively or abrasively perforating the tubing to create one or more openings. Perforating, however, requires additional time and equipment that increase the cost of the well.
Furthermore, current methods of opening the toe with hydraulic pressure limit the pressure test to pressures below the highest pressure the tubing will experience, to a maximum period of time, to a single test, or some combination of the above. This is particularly true in cemented environments where the inside of the tool is exposed to a cement slurry that contains particulate solids and which will ultimately harden.
Therefore, there exists a need for an improved method of opening the toe of the tubing after it is installed and pressure tested. The present disclosure describes improved devices and methods for opening the toe of tubing installed in a well. Some embodiment tools according to the present disclosure allow the pressure test to be conducted at the full burst pressure rating of the device, and allow sequential pressure tests to be performed. The devices and methods may also be readily adapted to other locations in the well and for other use in tools other than toe valves.